Sensors for the analysis of wastewater in wastewater treatment plants and the like are relatively susceptible to trouble if only because of the hostile measuring environment, i.e. wastewater. Further, electro-chemical sensor elements or reference elements each require a supply of an electrolyte in an electrolyte tank. If the sensor element or the reference element fails or if the electrolyte tank is empty, the relevant sensor or reference element has to be replaced or the respective electrolyte tank has to be filled with electrolyte. In case of malfunction, it is often not easy to determine which sensor or reference element has to be replaced. Replacing individual sensor elements or refilling the electrolyte tank is cumbersome, tedious and costly.
From DE 295 08 870 U1, a sensor arrangement is known that comprises a plurality of pH sensor elements. The housing and the electrolyte tanks are formed by a plurality of coaxially nested glass tubes. The housing, including the electrolyte tanks of glass, is very complex to manufacture, prone to break during handling, and unsuited for sensor elements with ion selective membranes required for measuring other parameters than the pH value.
A sensor cartridge is known from DE 83 19 463 U, wherein the different tanks and housings are formed by different separate components of glass and/or plastics. The sensor cartridge has to be assembled from the components mentioned. Assembly is complex and error-prone. It is difficult and tedious to achieve a fluid-tight sealing of the components made of different materials.
In view of this, it is an object of the invention to simplify or improve the manufacture and the properties of a waste water sensor cartridge having ion-selective membranes.